Marjorie Scardino is seen with members of Nokia’s board in 2011. Twitter’s dismal record of gender diversity on its board came under fire this year, prompting the company to announce on Dec. 5 that Scardino would be its first-ever female board member. Photo: Reuters

Twitter has named former Pearson CEO Marjorie Scardino to its board after the microblogging service faced criticism that it lacked women in its top ranks.

The appointment of Scardino, 66, is effective immediately, Twitter said Thursday in a filing. She led Pearson, the education and publishing company, from 1997 to last year. The addition of Scardino expands Twitter’s board to eight people.

The absence of women on Twitter’s board was “a joke,” Sallie Krawcheck, a former Bank of America executive, said last month at a Bloomberg conference. It showed Silicon Valley was no better than Wall Street when it came to female representation, she said.

Also on Thursday, Twitter launched a new form of targeted advertising, allowing companies to deliver “promoted tweets” to customers who show interest in the brand through web browsing.

The new service, “Tailored Audiences,” is now available globally, as “a new way for advertisers to define your own groups of existing and potential customers, and connect with them on Twitter with relevant messages,” the company said.

Twitter, which previewed the service in July, will be able to match advertisers and customers who have visited that company’s website, without necessarily clicking on a Twitter link.